[Bug target/71475] [5/6/7 Regression] Optimization of copying into long double looses bytes

[ch3root at openwall dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71475

--- Comment #6 from Alexander Cherepanov <ch3root at openwall dot com> ---
Ok, what about this:

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#include <string.h>
#include <stdio.h>

int main()
{
   long double d;
   char s[sizeof(long double)];

   memcpy(&d, "AAAAAAAAAAAAAAA", sizeof d);
   memcpy(&s, &d, sizeof s);

   printf("%s\n", s);
}
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Results:

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$ gcc -std=c11 -pedantic -Wall -Wextra test.c && ./a.out
AAAAAAAAAAAAAAA

$ gcc -std=c11 -pedantic -Wall -Wextra -O3 test.c && ./a.out
AAAAAAAA
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gcc version: gcc (GCC) 7.0.0 20160608 (experimental)